Contactless graphene conductivity mapping on a wide range of substrates with terahertz time-domain reflection spectroscopy.
Kamboj, Varun S
Jessop, David S
Nature Publishing Group
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Lin, H., Braeuninger-Weimer, P., Kamboj, V. S., Jessop, D. S., Degl'Innocenti, R., Beere, H., Ritchie, D., et al. (2017). Contactless graphene conductivity mapping on a wide range of substrates with terahertz time-domain reflection spectroscopy.. Scientific Reports, 7 (1. 10625)https://doi.org/10.1038/s41598-017-09809-7
We demonstrate how terahertz time-domain spectroscopy (THz-TDS) operating in reflection geometry can be used for quantitative conductivity mapping of large area chemical vapour deposited graphene films on sapphire, silicon dioxide/silicon and germanium. We validate the technique against measurements performed with previously established conventional transmission based THz-TDS and are able to resolve conductivity changes in response to induced back-gate voltages. Compared to the transmission geometry, measurement in reflection mode requires careful alignment and complex analysis, but circumvents the need of a terahertz transparent substrate, potentially enabling fast, contactless, in-line characterisation of graphene films on non-insulating substrates such as germanium.
H.L. and J.A.Z. acknowledge financial support from the EPSRC (Grant No. EP/L019922/1). P.B.W. acknowledges EPSRC Cambridge NanoDTC EP/G037221/1. R.D., H.E.B. and D. R. acknowledge financial support from the EPSRC (Grant No. EP/J017671/1, Coherent Terahertz Systems). S.H. acknowledges funding from the EPSRC (Grant No. EP/K016636/1, GRAPHTED).
UNIVERSITY COLLEGE LONDON (FB EPSRC) (EP/J017671/1)
EPSRC (via University of Leeds) (EP/P021859/1)
External DOI: https://doi.org/10.1038/s41598-017-09809-7
This record's URL: https://www.repository.cam.ac.uk/handle/1810/274072
Attribution 4.0 International
Licence URL: http://creativecommons.org/licenses/by/4.0/
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